Lift pontoon and dock

ABSTRACT

Pontoon structures, particularly a low-cost watercraft defining a plurality of isolated compartments vented at their tops with respect to each other and each compartment having an independent valve in its bottom. The isolation of the compartments assures stability or seaworthiness, while the venting of the compartments at their tops assures the use of compressed air for uniform control of water level in the compartments. The independent valve in the bottom of each compartment enables precise regulation of discharge and admission of seawater.

United States Patent Amirikian 1 Sept. 5, 1972 [54] LIFT PONTOON ANDDOCK [72] Inventor: Arsham Amirikian, 6526 Western Ave., Chevy Chase,Md. 20015 [22] Filed: Feb. 11, 1970 [21] Appl. No.: 10,436

[52] US. Cl. ..114/0.5 F, 114/45, 114/121, 61/65 [51] Int. Cl. ..B63b35/42, B63c 1/06 [58] Field of Search ..61/65, 66, 67, 48; 114/45, 114/5F, 46,121,125

[5 6] References Cited UNITED STATES PATENTS 849,378 4/1967 Donnelly..61/65 X 1,296,662 3/1919 Hohorst ..61/65 1,335,497 3/1920 Hamilton..61/65 3,332,248 7/1967 Burnett ..61/65 X Primary Examiner-JacobShapiro Attorney-David Semmes [57 ABSTRACT Pontoon structures,particularly a low-cost watercraft defining a plurality of isolatedcompartments vented at their tops with respect to each other and eachcompartment having an independent valve in its bottom. The isolation ofthe compartments assures stability or seaworthiness, while the ventingof the compartments at their tops assures the use of compressed air foruniform control of water level in the compartments. The independentvalve in the bottom of each compartment enables precise regulation ofdischarge and admission of seawater.

1 Claim, 5 Drawing Figures PATENTEIJ E SHEET 1 BF 2 INVENTORPATENTEBSEP" 5 I912 SHEET 2 0F 2 INVENTOR LIFT PONTOON AND DOCK Theinvention relates to a submersible pontoon structure and its waterballasting system.

The main object of the invention is to provide a compartmented pontoonwhich, through a specially devised water ballasting system, could besubmerged or floated to various drafts.

Another object of the invention is to utilized such -a pontoon, eithersingly or in multiple assemblies, as a lifting and lowering device fordocking and undocking of ships.

Still another object of the invention is to use such a pontoon, eithersingly or in multiple units, as a float or draft reducing device fortransfer or docking of ships.

In recent years, drydocking facilities for ship repairs and maintenancehave reached a critical stage by reasons of reduced efficiency anddecreased capacity. This deficiency is particularly noticeable infacilities servicing naval vessels where increased draft requirementshave restricted or eliminated the use of many existing dry docks. Also,due to the prevailing very high construction costs, the number of newdry docks built as replacement or additional facility has been small. Itis believed that the adoption and use of a more economical drydockingsystem envisioned by this invention would greatly alleviate thissituation.

In external view, the pontoon looks like an ordinary deck barge, with aflat top and bottom, and raked ends. However, internally, there are anumber of distinguishing features which form the basis of thisinvention. The function and advantages of these features 'will becomeapparent by the following detailed description of the invention whenconsidered in conjunction with the accompanying drawings wherein:

FIG. 1 is an isometric view of the pontoon, showing the basic framingarrangement and the compartmentatron.

FIG. la is an enlarged, fragmentary section, showing a semicircularventing hole cut in the transverse and longitudinal bulkhead adjacentits intersection with the deck;

FIG. 2 is an enlarged side elevation, partially in section, showing thecontrolling valve 3 mounted in the bottom of the hollow body andextending above the deck;

FIG. 3 is a schematic view, partially in phantom, showing the use of thepresent pontoon structure with docking blocks, inboard of flanking pierswith lift cables; and

FIG. 4 is a similar view, showing the pontoon structure, supporting avessel within flanking piers l 1.

It is composed of an outer shell or slab 1, transverse bulkheads A andlongitudinal bulkheads B. Through the bulkheads A and B the body of thepontoon is subdivided into a series of isolated compartments, each ofwhich is provided with a hole 2 at the bottom for ingress and egress ofthe water ballast, and a controlling valve 3. The bulkheads havewatertight connections along their bottom joints 4 and side joints 5.Along their top connections 6 with the deck shell, a series of smallsemi-circular holes 7 are provided for the diffusion of compressed air,which is introduced through an air duct 8 and inlets 9. By this uniquearrangement, while the water in the various compartments will remainseparated from each other, the pressure of the introduced or ventedcompressed air will be of the same intensity and diffuse uniformlythrough all the compartments. This, in turn, will assure two importantoperational advantages. First, with the valves 3 in the open position,when an air pressure is applied, or the prevailing'pressure is vented,the ballast water in all the compartments will rise or fall uniformly asit were a single compartment, and thus the water level is controlled bythe simple device of a single air line. Second, under externaldisturbing forces, when the pontoon tends to list or trim, the momentsproduced by the resulting shift of water in the compartments will beminimized by the presence of the separating watertight bulkheads. Thisis an important stability advantage and essential for the use of thepontoon as a float.

The pontoon will normally be built of steel. However, in certainapplication, reinforced concrete, plastics and other framing materialsmay also be used, according to comparative cost and servicerequirements.

As a water-ballasted floating craft, whose draft is regulated by asimple application of compressed air described in this invention, thepontoon can be used for many purposes. In some applications, it mayconstitute the whole facility; in others, it may be supplemented withadjuncts for the required service.

In its simplest form, requiring only a source of compressed air or acompressor, the pontoon, either singly or in a multi-unit assembly,could serve as a float or draft-reducer platform for docking deep draftvessels into relatively shallow dry docks or basins. In this function,which restores the use of the latter facility, the lift and the deliveryof the vessel is accomplished in a larger dry clock of sufficient depthfor the pontoon and the superposed vessel.

Another important use of the pontoon is as the main component andlifting device of a new type of a dock which may be designated as LiftDock. Such an application is shown diagrammatically in FIGS. 3 and 4. Inthis application, two flanking piers 11, supported on piles 10, form anopen slip or channel in which the pontoon submerges down or floats up bycontrolling the water ballast. Air lines 8 connected to a supplymanifold 12, mounted on the outboard edge of one of the piers ll,furnish the compressed air needed for the ballast control. To providestability in the submerged position of the pontoon, a set of cables 14,suspended from the inboard faces of the flanking piers l l, are attachedto the pontoon near its four corners. The sequence of operation of aLift Dock thus composed is as follows: Referring to FIG. 3, first thepontoon is floated to its maximum freeboard, by opening the water valves3 and blowing the water ballast, at which position, shown in solidlines, the pontoon deck is leveled and the docking blocks 15 are set.Next, the compressed air contained in the pontoon is vented throughvalves 16 located at the manifold 12, thus allowing the water ballast toenter into the compartments, causing submergence of the pontoon to thebottom of the slip,

' as shown by the dotted lines in FIGS. 3 and 4, at which time thefloating vessel 13 is brought into the channel and positioned fordocking. In the following step, the air venting valves 16 are closed,the compressed air is introduced into the pontoon to remove the waterballast and initiate the ascent. After contact is made with the bottomof the vessel 13, additional air is injected into the pontoon to removethe remaining ballast water and thus to create the needed buoyancy forthe lift of the vessel. In this final position, shown in solid lines inFIG. 4, with the pontoon afloat with a freeboard and the vesselsupported on the blocks 15, the water valves 3 in all the compartmentsare closed to complete the docking operation.

Normally the needed repairs to the vessel would be accomplished in placein this floating position. However, where a shallow basin or anunderwater support grid is available, the work can be performed moreadvantageously by setting the assembly on a fixed base. For thispurpose, the stabilizer cables 14 are detached and the assembly is movedas a float to the repair site, at which place the water valves 3 areopened to admit additional water ballast for setting the float on thesupport base. Obviously, the depth of water in such a basin at high tideshould be less than the depth of the pontoon, so that the pontoon deckwould remain above the surrounding water level and thus serve as a drywork platform.

Upon completion of the repair work in the basin, compressed air isapplied to remove the water ballast and refloat the assembly, at whichstage the water valves 3 are closed again. It is quite possible that theassembly in its free floating position may have some list and/or trim.To obtain the desired levelment, the water valves in the cornercompartments on low side or end are opened and, through injection ofadditional compressed air, a part of the remaining water ballast isejected from these compartments, thus creating the necessary balancingbuoyancy for an even keel flotation. When this condition is attained,the water valves are closed and the assembly is brought back to the LiftDock site. Here the stabilizer cables are reattached to the pontoon, thewater valves 3 in all the compartments, as well as the air ventingvalves 16 at the manifold 12, are opened to readmit ballast water forinitiating and continuing submergence of the pontoon until the vessel isfully water-borne. This completes the undocking operation.

The arrangement shown in FIG. 1 and described above constitutes thebasic concept of this invention. While certain deviations, either in thearrangement or details, as well as in the manner of applications, can beintroduced, it will be understood that such modifications may be madewithout departing from the spirit of the invention..F or example, insome applications it may be deemed desirable to leave certaincompartments permanently dry or buoyant, in which case the water inlethole 2 in the bottom and the air holes 7 at the top will be omitted. Inother instances, certain compartments may be left open to the seapermanently, in which case the controlling water valve 3 will beomitted.

Having thus described my invention, 1 claim:

1. A pontoon structure, comprising in combination:

A. a substantially hollow body defining end, side, deck, and bottomportions and including an air outlet;

B. a plurality of intersecting longitudinal and transverse bulkheads,vertically supported within said hollow body, so as to define a seriesof closed compartments, each of said bulkheads having an openingextending through its top portion adjacent to said deck, so as toprovide a passageway between said compartments fore and aft, as well aslaterally with respect to each other;

C. a valve fitted within the bottom of each compartment so as toindependently control ballast water level in each compartment; and

D. a source of compressed air communicating with said hollow body, atthe top thereof, so as to be distributed through each said opening intoeach compartment.

1. A pontoon structure, comprising in combination: A. a substantiallyhollow body defining end, side, deck, and bottom portions and includingan air outlet; B. a plurality of intersecting longitudinal andtransverse bulkheads, vertically supported within said hollow body, soas to define a series of closed compartments, each of said bulkheadshaving an opening extending through its top portion adjacent to saiddeck, so as to provide a passageway between said compartments fore andaft, as well as laterally with respect to each other; C. a valve fittedwithin the bottom of each compartment so as to independently controlballast water level in each compartment; and D. a source of compressedair communicating with said hollow body, at the top thereof, so as to bedistributed through each said opening into each compartment.